1. Field of the Invention
The present invention relates to a semiconductor and a process for production of the same, more particularly relates to a thin package semiconductor device and a process of production of the same.
2. Description of the Related Art
The most flexible type of thin package semiconductor device mounting a semiconductor element (LSI or other semiconductor chip) for the increase of pins, reduction of the pitch between connection terminals, and reduction of thickness and size of the device as a whole is the tape carrier package (TCP).
A TCP is produced by mounting a semiconductor element on an insulating tape substrate (usually a resin film) by tape automated bonding (TAB). Typically, first, a copper foil is attached to a resin film provided with a predetermined pattern of openings, then the copper foil is etched to pattern it to form predetermined copper leads. Next, a semiconductor element (semiconductor chip) is positioned and held within an opening of the resin film, a plurality of connection terminals of the chip (in general gold bumps) and a corresponding plurality of copper leads on the resin film are bonded together, then the semiconductor chip and part of the copper leads are sealed by a resin to complete a single semiconductor package unit. This operation is repeated for every opening while intermittently feeding the resin film, whereby a large number of semiconductor package units are formed on a single film. Finally, the large number of semiconductor package units formed along the longitudinal direction of the film are cut and separated from each other so as to obtain individual semiconductor packages.
FIG. 1 is a perspective view of a semiconductor device of the related art obtained by connecting a semiconductor chip and TCP leads. It shows the state before the individual TCPs are cut from the tape. The TCP 10 uses a resin film (for example, a polyimide resin film) 1 as a substrate and has leads 2 formed by etching of a copper foil on top. Further, sprocket holes 3 are formed at the two side edges of the resin film 1 for feeding the film. An opening 5 for accommodating a semiconductor chip 4 (in general called a xe2x80x9cdevice holexe2x80x9d) and window holes 9 are also formed in the center of the resin film 1 as illustrated.
The state of connection of the semiconductor chip and the leads of the package is shown in the sectional view of FIG. 2, which shows the center portion of the semiconductor device of FIG. 1 enlarged. A semiconductor chip 4 is positioned and placed in the device hole 5 of the resin film 1, then the front ends of the leads 2 are bonded on the bumps on the electrodes (normally projections formed by gold plating). The leads are normally bonded all together using a special bonding tool. Note that to assist the bonding of the bumps 6 with the front ends of the leads 2 comprised of copper, the bumps are gold plated in advance before the bonding step. Finally, while not shown in FIG. 1, the semiconductor chip 4 and the leads 6 are protected from the humidity, contamination, etc. of the ambient environment by sealing the two to cover them by a resin 7. As the sealing resin 7, use is made for example of an epoxy resin.
The above conventional semiconductor device however suffered from the following problems (a) to (e):
(a) There are limits to the reduction of the mounting height of the semiconductor chip on a resin film, so there are limits to the reduction of thickness of the semiconductor device. That is, the semiconductor device is fixed by thin copper leads projecting out in a bridge like manner into the opening of the resin film, so securing sufficient mounting strength requires that the copper leads, the resin film serving as the support member, and the device as a whole be at least a certain thickness. If reinforcing the strength by the resin sealed portion, a broad area has to be sealed thickly. It is difficult however to secure complete sealing across a broad area. Further, thick sealing runs counter to the desire to reduce thickness.
(b) Semiconductor chips become brittle and easily warpable when made thin enough for reducing the thickness of the semiconductor device. Each requires a special carrier. Handling is extremely complicated and a large number of steps are required. Further, improvement of the manufacturing yield also becomes difficult.
(c) The individual semiconductor chips have to be individually positioned and bonded in the openings of the resin film, so production of a large number of semiconductor packages requires a long, complicated production process.
(d) In the case of a multilayer semiconductor device obtained by stacking semiconductor chips in a plurality of layers, each individual semiconductor chip has to be positioned and bonded in the opening of the resin film, so the production process becomes even longer and more complicated.
(e) Not only is there a manufacturing variation in the thickness of the chips, but there is also variation in the individual mounting heights. As a result, a variation in height arises in the semiconductor devices. It is consequently difficult to conduct electrical tests all together before cutting and separating the film into the semiconductor package units.
An object of the present invention is to solve the above problems in the related art and provide a semiconductor device, in particular a thin semiconductor package, which reduces and simultaneously achieves a uniform mounting height, does not require complicated steps for mounting individual chips, improves the manufacturing yield, achieves a uniform height of the semiconductor device without being affected by the variation in thickness of the chips, and enables execution of electrical tests all together and a process for production of the same.
To achieve the above object, according to a first aspect of the present invention, there is provided a semiconductor device provided with an insulating tape substrate having through holes in the thickness direction; a semiconductor element mounted on a top surface of the tape substrate with its back surface exposed upward and its active surface facing downward; a sealing resin layer formed on the top surface of the tape substrate outside of the region in which the semiconductor device is mounted and sealing the area around the side surfaces of the semiconductor element; metal interconnections formed on the bottom surface of the tape substrate and blocking the bottom ends of the through holes of the tape substrate to define bottom portions; a solder resist layer covering the metal interconnections and the bottom surface of the tape substrate and having through holes in the thickness direction; external connection terminals projecting from the bottom surface of the metal interconnections and filling, passing through, and projecting downward through the through holes of the solder resist layer; connection terminals extending downward from the active surface of the semiconductor element and inserted in the through holes of the tape substrate; and a filler comprised of a conductive material filling the gaps between the connection terminals and the inside walls of the through holes of the tape substrate and electrically connecting the connection terminals and the metal interconnections.
According to the present invention, there is also provided a process of production of a semiconductor device of the first aspect, comprising forming through holes in the thickness direction in a tape substrate having an area able to accommodate a plurality of semiconductor package units and provided at its bottom surface with a metal interconnection layer and a solder resist layer and forming throughholes in the thickness direction in the solder resist layer; filling a conductive material in the through holes of the tape substrate in amounts incompletely filling the through holes; inserting connection terminals of a number of semiconductor elements required for forming a plurality of semiconductor package units into the corresponding through holes of the tape substrate and filling the gaps between the connection terminals and the inside walls of the through holes by the conductive material until about the top ends of the through holes; bonding and mounting semiconductor elements on the top surface of the tape substrate; forming a sealing resin layer covering the top surface of the tape substrate other than the regions where the semiconductor elements are mounted and sealing the area around the side surfaces of the semiconductor element; grinding and polishing to a predetermined thickness the top part of the sealing resin layer and the back surface portions of the semiconductor elements; and cutting the tape substrate into semiconductor package units to obtain individual semiconductor devices. By providing connection terminals extending downward from the active surface of the semiconductor element and inserted into the through holes of the tape substrate and a filler comprised of a conductive material filling the gap between the connection terminals and the inner walls of the through holes of the tape substrate and electrically connecting the connection terminals and metal interconnections, it is possible to directly bond the semiconductor element to the tape substrate at the active surface and possible to electrically connect the semiconductor element to the metal interconnection layer by the connection terminals inserted in the through holes of the tape substrate and the filler comprised of the conductive material filling the gap, so the device can be made thinner than the past while easily securing mounting strength compared with a structure of affixing a semiconductor element in an opening of a tape substrate by leads like in the related art.
Further, since the back surfaces of the semiconductor elements and the sealing resin layer can be ground and polished from the top to reduce the height to a predetermined value in a state with a large number of semiconductor elements fixed to the tape substrate and with the area around the side surfaces of the semiconductor elements sealed by a resin, the individual semiconductor chips can be handled in a thick state without being made thin, no complicated steps or special carriers are required as in the past, a large number of semiconductor package units can be produced all together while integrally fixed to the tape substrate, the heights of the semiconductor devices, that is, the semiconductor packages, can be made small and uniform, the electrical tests can be performed all at once, the production process is shortened and the manufacturing yield improved, and the devices can be made thinner than in the past.
Preferably, the semiconductor device is further provided with conductor columns passing through the resin sealing layer and the tape substrate at a region where the resin sealing layer is formed, having top ends exposed at the top surface of the resin sealing layer, and having bottom ends electrically connected to the metal interconnection layer or is further provided with, instead of the sealing resin layer, an insulating frame bonded to the top surface of the tape substrate other than at the region where the semiconductor element is mounted and surrounding the side surfaces of the semiconductor element with a gap and a resin sealing layer filling the gap and sealing the area around the side surfaces of the semiconductor element and further provided with conductor columns passing through the frame and the tape substrate at a region where the frame is formed, having top ends exposed at the top surface of the frame, and having bottom ends electrically connected to the metal interconnection layer. These preferred structures are particularly advantageous when applied to a multilayer semiconductor device. A multilayer semiconductor device produced in this way is comprised of a plurality of such semiconductor devices stacked in layers, wherein the semiconductor devices of each layer are connected with each other at the top ends of the conductor columns and the bottom ends of the external connection terminals. Preferably, the connection terminals extending downward from the active surface of the semiconductor element are bumps comprised of gold or copper. Preferably, the external connection terminals filling and passing through the openings of the solder resist layer are arranged a peripheral or area array mode according to the application of the semiconductor device or the requirements of the customer. Preferably, the filler is filled in the gaps between the connection terminals and the through holes of the tape substrate up to positions of substantially the top ends of the through holes. That is, the amount of the filler is set so that the total volume with the connection terminals of the semiconductor element inserted later becomes substantially equal to the volume of the through holes of the tape substrate (with bottom portions defined by the metal interconnections). Due to this, the connection terminals and metal interconnections are reliably connected and, simultaneously, overflow of excess conductive material from the top ends of the through holes is prevented. As the conductive material, use may be made of a low melting point metal or a conductive paste. Preferably, since the heights of the large number of semiconductor package units formed on the tape substrate are made uniform, it is possible to easily perform electrical tests all together after forming the sealing resin layer and before or after the grinding and the polishing.
Preferably, the tape substrate is of a size able to accommodate the plurality of semiconductor package units and is shaped as a disk of 2 to 12 inches in diameter. Due to this, it is possible to use existing grinding machines or cutting machines or other facilities for processing semiconductor wafers of the same size, so the cost of new equipment can be reduced by that amount.
According to a second aspect of the present invention, there is provided a semiconductor device provided with an insulating tape substrate having metal interconnections on the top surface; a semiconductor element mounted on a top surface of the tape substrate with its back surface exposed upward and its active surface facing downward; a sealing resin layer formed on the top surface of the tape substrate, sealing the area around the side surfaces of the semiconductor element, and filling the gap between the active surface of the semiconductor element and the top surface of the tape substrate; and at least one of conductor columns extending upward from the top surfaces of the metal interconnections, passing through the sealing resin layer at the area around the side surfaces of the semiconductor element, and having top ends exposed upward and of external connection terminals extending downward from the bottom surfaces of the metal interconnections, passing through the tape substrate, and projecting downward.
Typically, the top surface of the sealing resin layer and the back surface of the semiconductor element form substantially the same plane.
The semiconductor device of the second aspect of the present invention may be produced by one of the following three processes of production depending on whether it is provided with the conductor columns, the external connection terminals, or both.
First, there is provided a process of production of a semiconductor device comprising preparing a tape substrate having an area able to accommodate a plurality of semiconductor package units and provided at its top surface with metal interconnections; bonding connection terminals of active surfaces of a number of semiconductor elements required for forming the plurality of semiconductor package units to the top surfaces of the metal interconnections of the tape substrate to mount the semiconductor elements on the top surface of the tape substrate; forming conductor columns with bottom ends bonded to the top surfaces of the metal interconnections; forming a sealing resin layer sealing the area around the side surfaces of the semiconductor elements, including the metal interconnections and conductor columns, and filling the gaps between the active surfaces of the semiconductor elements and the top surface of the tape substrate; grinding and polishing to a predetermined thickness the top part of the sealing resin layer and the back surface portions of the semiconductor elements and exposing the top ends of the conductor columns upward; and cutting the tape substrate into semiconductor package units to obtain individual semiconductor devices.
Second, there is provided a process of production of a semiconductor device comprising preparing a tape substrate having an area able to accommodate a plurality of semiconductor package units, provided at its top surface with metal interconnections, having through holes in a thickness direction at positions corresponding to external connection terminals, and having bottom surfaces of the metal interconnections defining top ends of the through holes; bonding connection terminals of active surfaces of a number of semiconductor elements required for forming the plurality of semiconductor package units to the top surfaces of the metal interconnections of the tape substrate to mount the semiconductor elements on the top surface of the tape substrate; forming a sealing resin layer sealing the area around the side surfaces of the semiconductor elements, including the metal interconnections, and filling the gaps between the active surfaces of the semiconductor elements and the top surface of the tape substrate; then, in either order, grinding and polishing to a predetermined thickness the top part of the sealing resin layer and the back surface portions of the semiconductor elements and forming external connection terminals extending downward from the bottom surfaces of the metal interconnections defining the top ends of the through holes, filling the through holes, and projecting downward; and cutting the tape substrate into semiconductor package units to obtain individual semiconductor devices.
Third, there is provided a process of production of a semiconductor device comprising preparing a tape substrate having an area able to accommodate a plurality of semiconductor package units, provided at its top surface with metal interconnections, having through holes in a thickness direction at positions corresponding to external connection terminals, and having bottom surfaces of the metal interconnections defining top ends of the through holes; bonding connection terminals of active surfaces of a number of semiconductor elements required for forming the plurality of semiconductor package units to the top surfaces of the metal interconnections of the tape substrate to mount the semiconductor elements on the top surface of the tape substrate; forming conductor columns with bottom ends bonded to the top surfaces of the metal interconnections; forming a sealing resin layer sealing the area around the side surfaces of the semiconductor elements, including the metal interconnections and conductor columns, and filling the gaps between the active surfaces of the semiconductor elements and the top surface of the tape substrate; then, in either order, grinding and polishing to a predetermined thickness the top part of the sealing resin layer and the back surface portions of the semiconductor elements and exposing the top ends of the conductor columns upward and forming external connection terminals extending downward from the bottom surfaces of the metal interconnections defining the top ends of the through holes, filling the through holes, and projecting downward; and cutting the tape substrate into semiconductor package units to obtain individual semiconductor devices.
By having the bottom ends of the connection terminals projecting downward from the active surface of the semiconductor element be connected to the top surfaces of the metal interconnections on the top surface of the tape substrate, it is possible to further simplify the structure than when connecting the connection terminals and the metal interconnections through a filler in the through holes of the tape substrate as in the first aspect of the invention and therefore it is possible to further improve the productivity of thin semiconductor devices.
Further, in the same way as the first aspect of the invention, since the back surfaces of the semiconductor elements and the sealing resin layer can be ground and polished from the top to reduce the height to a predetermined value in a state with a large number of semiconductor elements fixed to the tape substrate and with the area around the side surfaces of the semiconductor elements sealed by a resin, the individual semiconductor chips can be handled in a thick state without being made thin, no complicated steps or special carriers are required as in the past, a large number of semiconductor package units can be produced all together while integrally fixed to the tape substrate, the heights of the semiconductor devices, that is, the semiconductor packages, can be made small and uniform, the electrical tests can be performed all at once, the production process is shortened and the manufacturing yield improved, and the devices can be made thinner than in the past.
According to a third aspect of the present invention, there is provided a semiconductor device provided with a resin member of a predetermined thickness; a semiconductor element sealed inside the resin member, having a back surface exposed at a top surface of the resin member, and having an active surface facing downward; metal interconnections formed on the bottom surface of the resin member; and connection terminals extending downward from the active surface of the semiconductor element and having a bottom end connected to top surfaces of the metal interconnections.
Typically, the top surface of the sealing resin layer and the back surface of the semiconductor element form substantially the same plane.
According to the present invention, there is also provided a process of production of a semiconductor device of the third aspect, comprising mounting on the top surface of a metal substrate having an area able to accommodate a plurality of semiconductor package units semiconductor elements by turning the active surfaces of semiconductor elements downward and bonding front ends of connection terminals to the metal substrate; covering the entire top surface of the metal substrate by a resin to form a resin member in which the semiconductor elements are sealed and to the bottom surface of which the metal substrate is bonded; then,
in either order, grinding and polishing to a predetermined thickness the top part of the sealing resin layer and the back surface portions of the semiconductor elements and patterning the metal substrate to form metal interconnections with top surfaces connected to the bottom ends of the connection terminals on the bottom surface of the resin member; and cutting the resin member into semiconductor package units to obtain individual semiconductor devices.
According to the present invention, there is also provided another process of production of a semiconductor device of the third aspect, comprising preparing a composite metal plate comprised of a metal substrate having an area able to accommodate a plurality of semiconductor package units and of an interconnection pattern comprised of a different type of metal from the metal substrate on its top surface; mounting semiconductor elements on the top surface of the composite metal plate by turning the active surfaces of semiconductor elements downward and bonding front ends of connection terminals to the composite metal plate; covering the entire top surface of the composite metal plate by a resin to form a resin member in which the semiconductor elements are sealed and to the bottom surface of which the composite metal plate is bonded; then, in either order, grinding and polishing to a predetermined thickness the top part of the resin member and the back surface portions of the semiconductor elements and etching away the metal substrate of the composite metal plate and leaving the interconnection pattern so as to form metal interconnections comprised of the interconnection pattern with top surfaces connected to the bottom ends of the connection terminals on the bottom surface of the resin member; and cutting the resin member into semiconductor package units to obtain individual semiconductor devices.
By not including a tape substrate, it is possible to further reduce the thickness compared with the first and third aspects of the present invention. At the same time, the number of members is reduced and structure is simpler, so a further higher productivity can be achieved.
Further, in the same way, since a large number of semiconductor elements are sealed in a single resin member and the back surfaces of the semiconductor elements and the resin member can be ground and polished from the top to reduce the height to a predetermined value, the individual semiconductor chips can be handled in a thick state without being made thin, no complicated steps or special carriers are required as in the past, a large number of semiconductor package units can be produced all together while integrally fixed in the resin member, the heights of the semiconductor devices, that is, the semiconductor packages, can be made small and uniform, the electrical tests can be performed all at once, the production process is shortened and the manufacturing yield improved, and the devices can be made thinner than in the past.
Preferably, the semiconductor device is further provided with a plurality of conductor columns passing through the resin member from the top surfaces of the metal interconnections, extending upward, and having top ends exposed at the top surface of the resin member. Due to this, it is also possible to easily obtain a multilayer semiconductor device comprised of a plurality of semiconductor devices stacked in layers, wherein the semiconductor devices of each layer are connected with each other at the top ends of the conductor columns and the bottom ends of the metal interconnections through connection bumps.
More preferably, the side surfaces of the conductor columns are exposed at the side surfaces of the resin member. Due to this, it is also possible to easily obtain a parallel semiconductor device comprised of a plurality of semiconductor devices connected to each other at their side surfaces, wherein the semiconductor devices adjoining each other at their sides are electrically connected with each other at the side surfaces of the conductor columns exposed at the side surfaces of the resin member. Further, it is also possible to easily obtain a multilayer parallel semiconductor device comprised of a plurality of semiconductor devices stacked in layers and connected to each other at their side surfaces, wherein the semiconductor devices of each layer are electrically connected with each other at the top ends of the conductor columns and the bottom ends of the metal interconnections through connection bumps and wherein the semiconductor devices adjoining each other at their sides are electrically connected with each other at the side surfaces of the conductor columns exposed at the side surfaces of the resin member.
Preferably, the semiconductor device is further provided with a solder resist layer covering the entire bottom surface of the resin member including the metal interconnections and connection bumps formed on the bottom surfaces of the metal interconnections, passing through the solder resist layer, and projecting downward.
Preferably, the semiconductor device is further provided with a capacitor sealed inside the resin member and directly connected with the metal interconnections. More preferably, the capacitor is a multilayer ceramic capacitor including inner electrodes each having the surface being perpendicular to the thickness direction of the resin member. Still more preferably, an inorganic filler is dispersed in the resin member. Due to this, it is possible to adjust the thermal expansion coefficient and the heat conductivity of the resin member to desired values.
According to the above aspects of the invention, further, it is possible to inspect individual semiconductor devices, select only the good ones, and produce a multilayer, parallel, and multilayer parallel type semiconductor devices with elements connected across layers and/or at their sides. Therefore, it is possible to further improve the product yield.